for sure

8 synonyms and 2 antonyms for for sure, grouped by meaning and by how common each one is.

Adverb — Without any doubt; certainly.

Synonyms

Everyday swaps

Common words most readers know — safe in any writing.

definitely certainly absolutely

Less common

Still standard English, but they carry more weight.

undoubtedly

Rare, literary or technical

Precise, but they will stand out — check the sense before using one.

without a doubt of course sure thing no problem

Synonyms by Meaning

1. adverb informal

Without any doubt; certainly.

“I can't say for sure whether the shop is open on Sundays.”

definitely certainly without a doubt undoubtedly

Opposites

maybe possibly

2. interjection informal

Used on its own to agree with someone or accept a request.

“"Can you send it over tonight?" "For sure."”

absolutely definitely of course sure thing no problem

How to use for sure

The word patterns that sound natural to a native speaker.

know for sure one thing's for sure that's for sure can't say for sure

Conversational. As an interjection it is especially common in North American and Australian speech; formal writing uses certainly or with certainty instead.

Frequently asked questions

What is the difference between for sure and surely?

For sure means with certainty and usually attaches to knowing or saying — "I don't know for sure". Surely expresses the speaker's expectation or appeal for agreement — "surely he told you?" — and in American English can also mean certainly.

Is "for sure" too casual for work emails?

As a one-word yes it is fine among colleagues but reads as offhand to clients or senior staff. Certainly, of course, or a plain confirmation of what you will do is safer in external correspondence.

People also searched

maybe certainly absolutely definitely possibly undoubtedly no problem sure thing

Nearby words

← Back to the full definition of for sure